// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/pickle.h"

#include <stdlib.h>

#include <algorithm> // for max()
#include <limits>

#include "base/bits.h"
#include "base/macros.h"
#include "base/numerics/safe_conversions.h"
#include "build/build_config.h"

namespace base {

// static
const int Pickle::kPayloadUnit = 64;

static const size_t kCapacityReadOnly = static_cast<size_t>(-1);

PickleIterator::PickleIterator(const Pickle& pickle)
    : payload_(pickle.payload())
    , read_index_(0)
    , end_index_(pickle.payload_size())
{
}

template <typename Type>
inline bool PickleIterator::ReadBuiltinType(Type* result)
{
    const char* read_from = GetReadPointerAndAdvance<Type>();
    if (!read_from)
        return false;
    if (sizeof(Type) > sizeof(uint32_t))
        memcpy(result, read_from, sizeof(*result));
    else
        *result = *reinterpret_cast<const Type*>(read_from);
    return true;
}

inline void PickleIterator::Advance(size_t size)
{
    size_t aligned_size = bits::Align(size, sizeof(uint32_t));
    if (end_index_ - read_index_ < aligned_size) {
        read_index_ = end_index_;
    } else {
        read_index_ += aligned_size;
    }
}

template <typename Type>
inline const char* PickleIterator::GetReadPointerAndAdvance()
{
    if (sizeof(Type) > end_index_ - read_index_) {
        read_index_ = end_index_;
        return NULL;
    }
    const char* current_read_ptr = payload_ + read_index_;
    Advance(sizeof(Type));
    return current_read_ptr;
}

const char* PickleIterator::GetReadPointerAndAdvance(int num_bytes)
{
    if (num_bytes < 0 || end_index_ - read_index_ < static_cast<size_t>(num_bytes)) {
        read_index_ = end_index_;
        return NULL;
    }
    const char* current_read_ptr = payload_ + read_index_;
    Advance(num_bytes);
    return current_read_ptr;
}

inline const char* PickleIterator::GetReadPointerAndAdvance(
    int num_elements,
    size_t size_element)
{
    // Check for int32_t overflow.
    int64_t num_bytes = static_cast<int64_t>(num_elements) * size_element;
    int num_bytes32 = static_cast<int>(num_bytes);
    if (num_bytes != static_cast<int64_t>(num_bytes32))
        return NULL;
    return GetReadPointerAndAdvance(num_bytes32);
}

bool PickleIterator::ReadBool(bool* result)
{
    return ReadBuiltinType(result);
}

bool PickleIterator::ReadInt(int* result)
{
    return ReadBuiltinType(result);
}

bool PickleIterator::ReadLong(long* result)
{
    // Always read long as a 64-bit value to ensure compatibility between 32-bit
    // and 64-bit processes.
    int64_t result_int64 = 0;
    if (!ReadBuiltinType(&result_int64))
        return false;
    // CHECK if the cast truncates the value so that we know to change this IPC
    // parameter to use int64_t.
    *result = base::checked_cast<long>(result_int64);
    return true;
}

bool PickleIterator::ReadUInt16(uint16_t* result)
{
    return ReadBuiltinType(result);
}

bool PickleIterator::ReadUInt32(uint32_t* result)
{
    return ReadBuiltinType(result);
}

bool PickleIterator::ReadInt64(int64_t* result)
{
    return ReadBuiltinType(result);
}

bool PickleIterator::ReadUInt64(uint64_t* result)
{
    return ReadBuiltinType(result);
}

bool PickleIterator::ReadFloat(float* result)
{
    // crbug.com/315213
    // The source data may not be properly aligned, and unaligned float reads
    // cause SIGBUS on some ARM platforms, so force using memcpy to copy the data
    // into the result.
    const char* read_from = GetReadPointerAndAdvance<float>();
    if (!read_from)
        return false;
    memcpy(result, read_from, sizeof(*result));
    return true;
}

bool PickleIterator::ReadDouble(double* result)
{
    // crbug.com/315213
    // The source data may not be properly aligned, and unaligned double reads
    // cause SIGBUS on some ARM platforms, so force using memcpy to copy the data
    // into the result.
    const char* read_from = GetReadPointerAndAdvance<double>();
    if (!read_from)
        return false;
    memcpy(result, read_from, sizeof(*result));
    return true;
}

bool PickleIterator::ReadString(std::string* result)
{
    int len;
    if (!ReadInt(&len))
        return false;
    const char* read_from = GetReadPointerAndAdvance(len);
    if (!read_from)
        return false;

    result->assign(read_from, len);
    return true;
}

bool PickleIterator::ReadStringPiece(StringPiece* result)
{
    int len;
    if (!ReadInt(&len))
        return false;
    const char* read_from = GetReadPointerAndAdvance(len);
    if (!read_from)
        return false;

    *result = StringPiece(read_from, len);
    return true;
}

bool PickleIterator::ReadString16(string16* result)
{
    int len;
    if (!ReadInt(&len))
        return false;
    const char* read_from = GetReadPointerAndAdvance(len, sizeof(char16));
    if (!read_from)
        return false;

    result->assign(reinterpret_cast<const char16*>(read_from), len);
    return true;
}

bool PickleIterator::ReadStringPiece16(StringPiece16* result)
{
    int len;
    if (!ReadInt(&len))
        return false;
    const char* read_from = GetReadPointerAndAdvance(len, sizeof(char16));
    if (!read_from)
        return false;

    *result = StringPiece16(reinterpret_cast<const char16*>(read_from), len);
    return true;
}

bool PickleIterator::ReadData(const char** data, int* length)
{
    *length = 0;
    *data = 0;

    if (!ReadInt(length))
        return false;

    return ReadBytes(data, *length);
}

bool PickleIterator::ReadBytes(const char** data, int length)
{
    const char* read_from = GetReadPointerAndAdvance(length);
    if (!read_from)
        return false;
    *data = read_from;
    return true;
}

PickleSizer::PickleSizer() { }

PickleSizer::~PickleSizer() { }

void PickleSizer::AddString(const StringPiece& value)
{
    AddInt();
    AddBytes(static_cast<int>(value.size()));
}

void PickleSizer::AddString16(const StringPiece16& value)
{
    AddInt();
    AddBytes(static_cast<int>(value.size() * sizeof(char16)));
}

void PickleSizer::AddData(int length)
{
    CHECK_GE(length, 0);
    AddInt();
    AddBytes(length);
}

void PickleSizer::AddBytes(int length)
{
    payload_size_ += bits::Align(length, sizeof(uint32_t));
}

void PickleSizer::AddAttachment()
{
    // From IPC::Message::WriteAttachment
    AddInt();
}

template <size_t length>
void PickleSizer::AddBytesStatic()
{
    DCHECK_LE(length, static_cast<size_t>(std::numeric_limits<int>::max()));
    AddBytes(length);
}

template void PickleSizer::AddBytesStatic<2>();
template void PickleSizer::AddBytesStatic<4>();
template void PickleSizer::AddBytesStatic<8>();

Pickle::Attachment::Attachment() { }

Pickle::Attachment::~Attachment() { }

// Payload is uint32_t aligned.

Pickle::Pickle()
    : header_(NULL)
    , header_size_(sizeof(Header))
    , capacity_after_header_(0)
    , write_offset_(0)
{
    static_assert((Pickle::kPayloadUnit & (Pickle::kPayloadUnit - 1)) == 0,
        "Pickle::kPayloadUnit must be a power of two");
    Resize(kPayloadUnit);
    header_->payload_size = 0;
}

Pickle::Pickle(int header_size)
    : header_(NULL)
    , header_size_(bits::Align(header_size, sizeof(uint32_t)))
    , capacity_after_header_(0)
    , write_offset_(0)
{
    DCHECK_GE(static_cast<size_t>(header_size), sizeof(Header));
    DCHECK_LE(header_size, kPayloadUnit);
    Resize(kPayloadUnit);
    header_->payload_size = 0;
}

Pickle::Pickle(const char* data, int data_len)
    : header_(reinterpret_cast<Header*>(const_cast<char*>(data)))
    , header_size_(0)
    , capacity_after_header_(kCapacityReadOnly)
    , write_offset_(0)
{
    if (data_len >= static_cast<int>(sizeof(Header)))
        header_size_ = data_len - header_->payload_size;

    if (header_size_ > static_cast<unsigned int>(data_len))
        header_size_ = 0;

    if (header_size_ != bits::Align(header_size_, sizeof(uint32_t)))
        header_size_ = 0;

    // If there is anything wrong with the data, we're not going to use it.
    if (!header_size_)
        header_ = NULL;
}

Pickle::Pickle(const Pickle& other)
    : header_(NULL)
    , header_size_(other.header_size_)
    , capacity_after_header_(0)
    , write_offset_(other.write_offset_)
{
    Resize(other.header_->payload_size);
    memcpy(header_, other.header_, header_size_ + other.header_->payload_size);
}

Pickle::~Pickle()
{
    if (capacity_after_header_ != kCapacityReadOnly)
        free(header_);
}

Pickle& Pickle::operator=(const Pickle& other)
{
    if (this == &other) {
        NOTREACHED();
        return *this;
    }
    if (capacity_after_header_ == kCapacityReadOnly) {
        header_ = NULL;
        capacity_after_header_ = 0;
    }
    if (header_size_ != other.header_size_) {
        free(header_);
        header_ = NULL;
        header_size_ = other.header_size_;
    }
    Resize(other.header_->payload_size);
    memcpy(header_, other.header_,
        other.header_size_ + other.header_->payload_size);
    write_offset_ = other.write_offset_;
    return *this;
}

bool Pickle::WriteString(const StringPiece& value)
{
    if (!WriteInt(static_cast<int>(value.size())))
        return false;

    return WriteBytes(value.data(), static_cast<int>(value.size()));
}

bool Pickle::WriteString16(const StringPiece16& value)
{
    if (!WriteInt(static_cast<int>(value.size())))
        return false;

    return WriteBytes(value.data(),
        static_cast<int>(value.size()) * sizeof(char16));
}

bool Pickle::WriteData(const char* data, int length)
{
    return length >= 0 && WriteInt(length) && WriteBytes(data, length);
}

bool Pickle::WriteBytes(const void* data, int length)
{
    WriteBytesCommon(data, length);
    return true;
}

void Pickle::Reserve(size_t length)
{
    size_t data_len = bits::Align(length, sizeof(uint32_t));
    DCHECK_GE(data_len, length);
#ifdef ARCH_CPU_64_BITS
    DCHECK_LE(data_len, std::numeric_limits<uint32_t>::max());
#endif
    DCHECK_LE(write_offset_, std::numeric_limits<uint32_t>::max() - data_len);
    size_t new_size = write_offset_ + data_len;
    if (new_size > capacity_after_header_)
        Resize(capacity_after_header_ * 2 + new_size);
}

bool Pickle::WriteAttachment(scoped_refptr<Attachment> attachment)
{
    return false;
}

bool Pickle::ReadAttachment(base::PickleIterator* iter,
    scoped_refptr<Attachment>* attachment) const
{
    return false;
}

bool Pickle::HasAttachments() const
{
    return false;
}

void Pickle::Resize(size_t new_capacity)
{
    CHECK_NE(capacity_after_header_, kCapacityReadOnly);
    capacity_after_header_ = bits::Align(new_capacity, kPayloadUnit);
    void* p = realloc(header_, GetTotalAllocatedSize());
    CHECK(p);
    header_ = reinterpret_cast<Header*>(p);
}

void* Pickle::ClaimBytes(size_t num_bytes)
{
    void* p = ClaimUninitializedBytesInternal(num_bytes);
    CHECK(p);
    memset(p, 0, num_bytes);
    return p;
}

size_t Pickle::GetTotalAllocatedSize() const
{
    if (capacity_after_header_ == kCapacityReadOnly)
        return 0;
    return header_size_ + capacity_after_header_;
}

// static
const char* Pickle::FindNext(size_t header_size,
    const char* start,
    const char* end)
{
    size_t pickle_size = 0;
    if (!PeekNext(header_size, start, end, &pickle_size))
        return NULL;

    if (pickle_size > static_cast<size_t>(end - start))
        return NULL;

    return start + pickle_size;
}

// static
bool Pickle::PeekNext(size_t header_size,
    const char* start,
    const char* end,
    size_t* pickle_size)
{
    DCHECK_EQ(header_size, bits::Align(header_size, sizeof(uint32_t)));
    DCHECK_GE(header_size, sizeof(Header));
    DCHECK_LE(header_size, static_cast<size_t>(kPayloadUnit));

    size_t length = static_cast<size_t>(end - start);
    if (length < sizeof(Header))
        return false;

    const Header* hdr = reinterpret_cast<const Header*>(start);
    if (length < header_size)
        return false;

    if (hdr->payload_size > std::numeric_limits<size_t>::max() - header_size) {
        // If payload_size causes an overflow, we return maximum possible
        // pickle size to indicate that.
        *pickle_size = std::numeric_limits<size_t>::max();
    } else {
        *pickle_size = header_size + hdr->payload_size;
    }
    return true;
}

template <size_t length>
void Pickle::WriteBytesStatic(const void* data)
{
    WriteBytesCommon(data, length);
}

template void Pickle::WriteBytesStatic<2>(const void* data);
template void Pickle::WriteBytesStatic<4>(const void* data);
template void Pickle::WriteBytesStatic<8>(const void* data);

inline void* Pickle::ClaimUninitializedBytesInternal(size_t length)
{
    DCHECK_NE(kCapacityReadOnly, capacity_after_header_); // << "oops: pickle is readonly";
    size_t data_len = bits::Align(length, sizeof(uint32_t));
    DCHECK_GE(data_len, length);
#ifdef ARCH_CPU_64_BITS
    DCHECK_LE(data_len, std::numeric_limits<uint32_t>::max());
#endif
    DCHECK_LE(write_offset_, std::numeric_limits<uint32_t>::max() - data_len);
    size_t new_size = write_offset_ + data_len;
    if (new_size > capacity_after_header_) {
        size_t new_capacity = capacity_after_header_ * 2;
        const size_t kPickleHeapAlign = 4096;
        if (new_capacity > kPickleHeapAlign)
            new_capacity = bits::Align(new_capacity, kPickleHeapAlign) - kPayloadUnit;
        Resize(std::max(new_capacity, new_size));
    }

    char* write = mutable_payload() + write_offset_;
    memset(write + length, 0, data_len - length); // Always initialize padding
    header_->payload_size = static_cast<uint32_t>(new_size);
    write_offset_ = new_size;
    return write;
}

inline void Pickle::WriteBytesCommon(const void* data, size_t length)
{
    DCHECK_NE(kCapacityReadOnly, capacity_after_header_); // << "oops: pickle is readonly";
    MSAN_CHECK_MEM_IS_INITIALIZED(data, length);
    void* write = ClaimUninitializedBytesInternal(length);
    memcpy(write, data, length);
}

} // namespace base
